{
  "lesson": {
    "id": 1,
    "title": "Functions and arrays",
    "language": "javascript",
    "level": "beginner"
  },
  "example": {
    "code": "const double = (numbers) => numbers.map((n) => n * 2);",
    "input": [
      1,
      2,
      3
    ],
    "output": [
      2,
      4,
      6
    ]
  },
  "exercise": {
    "task": "Write a function that returns only even numbers.",
    "input": [
      1,
      2,
      3,
      4,
      5,
      6
    ],
    "expected": [
      2,
      4,
      6
    ]
  }
}